System of electrical intercommunication.



No. 68I,95|. Patented Sept. 3, 190|.

' E. A. CLARK.

SYSTEM 0F ELECTRICAL INTE'RCOMMUNICATION.

I (Application lcd June 8, 1896.) (No Model.) 3 Sheets-Sheet l.

No. 68|,95L Patented Sept. 3, |901. E. A. CLARK.

SYSTEM 0F ELECTRICAL INTERCOMMUNICATION.

(Application med June 8, 1896.

a Sheets-sheet 2.

(No Model.)

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E. A. CLARK.

SYSTEM 0F ELECTRICAL INTERCOMMUNICATIUN.

(Application led June S, 1898.) (No Model.) 3 Sheets-Sheet 3.

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UNITED STATES PATENT OEEICEo EMERY A. CLARK, OF SIOUX CITY, IOWA,ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE CLARK AUTOMATIC TELEPHONESWITCH-BOARD COM- PANY, OF PROVIDENCE, RHODE ISLAND.

SYSTEM OF ELECTRICAL INTERCOIVIIVIUNICATION.

SPECIFICATION forming part of Letters Patent N o. 681,951, datedSeptember 3, 1901.

Application filed .Tune 8, 1896. Serial No. 594,767. (No model.)

T0 a/ZZ whom it may concern.-

Beit known that I, EMERY A. CLARK, a citizen of the United States,residing at Sioux City, in the county of Woodbury and State of Iowa,have invented certain new and. useful Improvements in Systems ofElectrical Intercommunication; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

My invention relates to improvementsin instruments used in connectionwith systems of electrical intercommunication, and particularlyautomatic telephone-exchange systems; and it consists in the improvedtrans-l mitter and receiver, which will be hereinafter fully described,and particularly pointed out in the claims.

My invention is especially designed for use in connection with thesystem of electrical intercommunication described in Patent No. 498,236,granted to me May 30, 1893, in which such connections are described asbeing established between service instruments-such as telephones,telegraph instruments, &c. which are stationed at outlying points in thesystem determined by the subscribers and a central switchboard, so thatany one or more of the subscribers can place himself or themselves incommunication with each other automatically without calling upon a thirdperson at a central office to make the desired connection.

The object of my present invention is to provide a transmitter and areceiver by the use of which the action of the system will be renderedmore certain, the maintenance thereof more economical, and theestablishment of any desired connection easily and rapidly accomplished.

I-Ieretofore the main difculty that has been developed in connectionwith systems for automatically establishing connections between two ormore subscribers has been that of providing for the synchronous movementof the indicator of the transmitter and the switchwheel of the receiverunder the control of each subscriber. It is necessary that these twoparts always occupy corresponding positions in order that anautomaticexchange system may be practical, because otherwise there isextreme difculty in providing means whereby a subscriber can ascertainthe relative position of the switch-wheel of his receiver and know whataction to take in order to cause such switch-Wheel to establish anydesired connection.

In accomplishing the object of my invention I have provided for acontinuously-forward movement of the switch-Wheel of the receiver,making use of a circuit making and breaking mechanism operated throughthe movement of the dial of the transmitter to cause the switch-wheel ofthe receiver to move forward with a step-by-step movement with eachforward movement of the dial and to be always in unison therewith.

The indicator of the improved transmitter which I have devised consistsin its present form of a revoluble dial having thereon the names,numbers, or other designations of the connections which it is desired toestablish, and means are provided for moving the dial relative to afixed point continuously forward, so that any desired name, number, orother designation may be placedin coincidence with such point. Duringthe movement of the indicator to the desired position a circuit makingand breaking mechanism is brought into action which interrupts or breaksthe circuit each time a name, number, or other designation on the dialpasses the fixed point before referred to, thereby causing a movement ofthe switch-Wheel vof the receiver corresponding to that undergone by thedial of the transmitter. The number of names, numbers, or otherdesignations on the dial corresponds with the number of teeth formed onthe switch- Wheel, and as a forward movement of the switch-Wheelcorresponding to that of the dial takes place each time that the dial ismoved it will be seen that the dial and the switchwheel movesynchronously and are always in unison. Means are further provided inthe transmitter for preventing the making of superfluous contactsthrough the revolution of the dial and for insuring the stoppage of thedial at such a point as to leave the circuit open, so that no waste ofthe current established will take place. A great economy in theoperation of the system is thus effected.

The receiver which I make use of has for its principal feature arevoluble switch-wheel which rotates in the center of a circular seriesof contact-points equal in number to the number of teeth formed on saidswitch-wheel or the number of names, numbers, or other designations onthe face of the dial of the transmitter. To the switch-wheel is rigidlyattached an arm which is adapted to successively contact with each ofthe contact-points circularly arranged around-the sam e,and thus toestablish connection between the service instruments of the subscribers.The circuits of this system are such that when the switchwheel hasreached a position corresponding to that occupied by the indicator ofthe transmitter a connection is established between the serviceinstrument of the subscriber who is operating his transmitter and thatof the person whose name, number, or other designation appears on theface of the subscribers dial in coincidence with the xed point thereon.

My invention is fully illustrated in the drawings, which accompany andform a part of this application, in which the same reference-lettersrefer to the same or corresponding parts, and in which- Figure l is afront View of my transmitter, the indicatordial being partially brokenaway to show the arrangement of the mechanism for operating the same.Fig. 2 is a side elevation of my transmitter, a portion of the casebeing broken away to show in elevation the worm mechanism for causingmovement of the dial. Fig. 3 is also a side elevation of my transmitter,a portion of the case being broken away to show the circuit making andbreaking mechanism. Fig. 4 is a detail View of the circuit making andbreaking mechanism, the full lines showing the parts in the positionthey assume when the circuit is made and the dotted lines when thecircuit is broken. Fig. 5 is a detail View of the ratchetand-pawlmechanism used to prevent backward movement of the indicator. Fig. 6 isa side elevation of the receiver, showing the switch-wheel thereof andthe lever fixed thereto which establishes connection with the circularseries of contact-points arranged at the base thereof. Fig. 7 is an endelevation of the receiver, showing the magnets and their armature. Fig.8 is also an end elevation of the receiver, but is so taken as to showthe end of the magnets opposite to that shown in Fig. 7. Fig. 9 is a topplan view of the receiver, showing the circular series of contactpoints.Fig. lO is a diagrammatic view of an automatic telephone-exchangecomposed of three members.

I have stated that my invention consists in the novel construction of mytransmitter and of my receiver. I will now proceed to describe theseinstruments in detail and then describe the system in connection withwhich they are represented as being used.

Transmtter.-Referring to the drawings, and especially to Figs. l to 5,inclusive, G is a case, of metal or other suitable material, preferablynickel-plated in order to give the same a neat and attractiveappearance. This case is circular in form and is provided with a baseI-I, of wood or other insulating material. To the wooden base IFI issecured the base-plate D, which is provided in the center of the casewith a boss d, perforated in order to permit the passage therethrough ofthe shaft d', upon which the indicator or dial B is mounted, as well asthe gearwheel C, and with suitable bearings for the worm-shaft E, whichis adapted to cause the revolution of the gear-wheel C and is operatedby revolution of the crank F, attached thereto. The base-plate D and allthe parts connected therewith are placed in connection with the outsidecircuit through the switch-wire Z, which enters, as shown in Fig. 2,through a depression in the center of the base H.

The transmitter is provided with a glass cover A in order to prevent theentrance of dust and dirt. Immediately beneath the cover appears therevoluble indicator or dial B, upon which the names, numbers, or otherdesignations of the connections which it is desired to establish throughthe use of the transmitter are indicated. In the drawings I have shownthe dial as being constructed for a system of eighty subscribers andhave indicated the position of the subscribers on the dial by the use ofnumbers, only every fifth number being Written, however, forconvenience. I have also shown a number of blank spaces CL, which are toprovide for the addition of more subscribers to the system after theregular dial-plate has been completely filled. These blank spaces may bescattered uniformly around the circumference of the dial, as shown,orgrouped together; but the arrangement which I illustrate is thatpreferred. Instead of representing the subscribers by the use of numbersthe names of the subscribers can be written upon the face of the dial orany other designation can be employed. In my transmitter theestablishment of any desired connection is effected by the movement ofthe dial relative to a Xed point and the consequent making and breakingof the circuit between the transmitter and the receiver a number oftimes corresponding to the distance of the name of the subscriber withwhom the connection is desired to be established from that of thesubscriber operating his transmitter. In the drawings I have utilized todefine this ixed point a panel g, painted on the face of the cover forthe dial. This beneath the same.

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transmitter the dial is turned until the number of the subscriber Withwhom connection is desired to be established appears underneath thepanel. The revolution of the dial is occasioned through the revolutionof the gear-Wheel C, mounted on the shaft CZ, on which the dial is alsomounted. The gearwheel C is formed upon its periphery with a series ofdepressions or grooves, with which engage the Worm-threads uponWorm-shaft E. To one end of the shaft E is attached the crank F.Movement of the dial can thus be effected by revolution of the crankFbut the connection between the worm-shaft and dial is such that themovement of the dial will be slow and uniform and will take placeWithout sudden jerks and movements. In my present construction therevolution of the dial through a single space is effected by a halfturnof the crank F, and therefore of the Worm-shaft E. The direction ofmovement of the crank-shaft is continuously forward, movement in theopposite direction being prevented by the ratchet-wheel I, which ismounted upon the Worm-shaft E and is engaged by a suitablespring-pressed pawl.

The circuit making and breaking mechanism which I have devised for usewith my present style of transmitter consists of a revoluble body in thecircuit of the transmittercase, which makes contact with a suitablecontacting device insulated from the case and forminga portion of thereturn-circuit of the receiver each time the revoluble dial movesthrough a single space. I prefer to place the revoluble circuit makingand breaking device upon an extended portion ofthe wormshaft E, as bythis means I am enabled to make the operation of the same coincide withthe movement of the Worm-shaft, and thereby of the dial, and to use assuch device projections equal in number to the number of complete spacesthrough Which the dial is turned by each revolution of the shaft E,which contact with a suitably-placed spring in the return-circuit to thereceiver. As in my present construction the dial is caused to movethrough two spaces by each revolution of the crank, the circuit makingand breaking device is in the form of a two-pronged fork K, which ismounted upon the inner end of the worm-shaft E, as shown in Fig. l, andcontacts during its movement with the contactspring t'. Thecontact-spring t' is bifurcated in order to insure more certain contact,is secured to an insulated base-plate h, which in turn is fastened tothe base H, and is grounded through the leading-wire Y. Thecontactspring is thus insulated from the case of the transmitter and allthe parts therein except when the circuit making and breaking fork Kmakes contact therewith. The spring is so placed that contact is thusmade twice during each complete revolution of the circuit making andbreaking device or each time that the revoluble dial of thetransmittermoves througha complete space. In other Words, the connectionis such that the circuit from the transmitter to the receiver is madeand broken each time the dial moves through a complete space, so thatthe switchwheel of the receiver may move synchronously with the dial.

It is important in the operation of circuit making and breaking devicesto prevent the making of additional contacts which Would throw the dialof the transmitter and the switch-wheel of the receiver out of unison.In order to prevent the making of such additional contacts, I secure tothe inner surface of the contact-sprin g a block of insulating materialmths upper ed ge of which is beveled inwardly. The circuit making andbreaking fork K first strikes the insulated block n in its revolutionand as it continues its movement presses the contact-spring t' outwarduntil it passes beyond the edge of the insulated block n and makescontact with the spring t'. The formation of the edge of the block issuch as to prevent a return movement of the circuit making and breakingdevice, so that only a continuously-forward movement of the same cantake place. The circuit through the transmitter is thus completed, butis broken as the circuit making and breaking fork passes the end of thecontact-spring t and is not completed until the fork K has been turnedthrough another half a revolution, for the distance between the point ofsupport of the circuit making and breaking fork K and that of thecontact-spring t' is such that the inward movement of the contact-springincident to its release from the outward pressure of the circuit makingand breaking device is not suflicient to enable it to make contact withsuch device. The number of contacts which the circuit making andbreaking device makes with the contact-spring is thus determined solelyby the movement of such spring and is limited to two contacts duringeach complete revolution of the crank-shaft E or a single contact duringeach forward movement of the revoluble dial through a complete space.

In order to prevent waste of current and to insure the practical successof my system, it is necessary to provide means for insuring the stoppageof the circuit making and breaking device at such a point as to leavethe circuit through the transmitter open. I accomplish this result in mypresent construction by the use of the spring J, Which is secured at oneend to the base-plate D and presses with its upper end against aflattened portion of the worm-shaft E. This spring insures the stoppageof the movement -of such worm-shaft at such a position that the circuitmaking and breaking fork K is out of contact with the contact-spring 'L'and the circuit through the transmitter is broken.

The operation ot' my transmitter is as follows: Normally the dial ot'the transmitter is so placed that the name of the subscriber lto whomthe transmitter belongs appears IOO IIO

through the panel g. When Ait is desired toestablish any givenconnection, the crank F is turned until by successive movements the dialhas been rotated sufficiently to cause the name, number, or otherdesignation of the subscriber with Whom the connection is desired to beestablished to appear beneath the panel g. This action is caused by theengagement of the threads of the worm-shaft E with the grooves cut inthe periphery of the gear-wheel C, which is mounted, as beforedescribed, upon the same shaft d to which is keyed the revoluble dial B.During the forward movement of the dial the circuit through thetransmitter has been made and and distinct and insure the proper actionofk the circuit. The stoppage of the Worm-shaft E in such position as toleave the circuit through the transmitter open is insured by the actionof the ilat spring J, which presses against a flattened portion of suchwormshaft. It is thus apparent that while the movement of the dial,Which has resulted in the bringing of the name of the subscriber withwhom the connection is desired to be established underneath the panel ghas been taking place, the switch of the receiver has been actuated anumber of times corresponding to the number of names, numbers, or otherdesignations which have successively passed beneath the panelg,so thatthe switchwheel of the receiver when the movement of the transmitter hasceased is in a position coincident with that of the dial or is in suchposition as to complete the circuit between the service instruments ofthe two subscribers.

Beamten-The receiver which I have devised is formed with a base-plate ofWood or other insulating material, upon which are arranged in circularseries contact-points cor-Y ceiver or with the number of names, num- Therelative device is rigidly secured to the switch-wheel.

and is adapted to successively pass over and make contact with theseries of contact-points arranged circularly on the base of thereceiver, contact being made at one time with only one of such points.The switch-wheel of the receiver is placed in unison with the revolubledial of the transmitter at the bcginning of its operation or in such aposition that the contacting device fastened thereto makes contact withthe contact-point which is in the circuit of the service instrument ofthe subscriber to whom the transmitter and receiver belong. As thenumber of teeth on the `switch-wheel of the receiver, the number ofcontact-points circularly arranged on the base thereof, and the numberof names, numbers, or other designations on the face of the dial areallequal and as the mechanism arranged to propel the switch-wheel with astep-by-step movement is so operated as to cause the switchwheel toalways coincide in position With the position of the revoluble dial, itwill .be seen that the contactpoint with which the contact devicefastened on the switch-wheel makes contact coincides with the name,number, or other designation appearing beneath the panel g on the faceof the transmitter. The connection established by the revolution of thedial of the transmitter is thus always with the subscriber whose name,number, or other designation appears beneath the panel g.

My receiver is illustrated in detail in Figs. 6 to 9, inclusive.Referring to these gures, R represents the base of the receiver and, asabove stated, is made of wood or other insulating material. 4On thisbase are arranged in circular series contact-points corresponding innumber to the total number of subscribers in the system. Each of thesecontact-points is connected by an insulated Wire p in a suitable manner,such as by the twisted connection shown at p', with a service instrumentand also, as will hereinafter be more fully described, with thecorresponding contact-points of all the other receivers in the system.The receiver which I illustrate is designed for use in a system ofeighty subscribers; but additional expansion of the system is renderedpossible through the spaces a, left for the insertion ot additionalcontactpoints. These spaces are preferably arranged in regular seriesamong the contact-points and must of course coincide in position withthe position of similar spaces on the face of the revoluble dial of thetransmitter. I have numbered the contact-points with numberscorresponding with the numbers on the face of the dial, thus indicatingthat the position of the contact-points coincides with the position ofthe names, numbers, or other designations on such dial. In order toeconomize space rand to reduce the size of the switch-wheel and partsconnected therewith, I have further arranged the contact-points inconcentric series and have staggered the same relatively to each IOO4IIO

other, so that the contact-spring T, which is arranged to sweep overboth circles of contact-points, will, while contacting with each pointin succession, make contact at any one time with only a singlecontact-point. Centrally within the base upon an upward extension of thebase plate S is revolubly mounted the switch-wheel W. The switchwheel Wis formed with a toothed periphery, the teeth of which slant only in onedirection and are equal in number to the number of contact-pointsarranged in circular series below the same. To the switch-wheel isrigidly secured the bent lever U, to the lower end of which is attachedthe contact-spring T. Movement of the switch-wheel results incorresponding movement of the contact-lever U, and the size of the teethof such switch-wheel is so regulated that the forward movement of thesame the distance of a single tooth is sufficient to move thecontact-spring T from one contact-point to that next adjacent thereto.The step-by-step forward movement of the switch-wheel is effected by theaction of the stepping -levers V and V', which are mounted diametricallyopposite to each other in trunnion-bearings formed in the base-plate Sand are formed with toothed surfaces which correspond in shape and sizeto the space between adjacent teeth of the switch-wheel. The screws o,which serve to support the stepping-levers V and V', are capable ofadjustment, so that the stepping-levers may be staggered sufficiently tocause one of such levers to strike against the side of the teeth of theswitch-wheel with which it will next come in contact when the othersteppinglever is in engagement with the switch-wheel. Thestepping-levers alternately engage with the switch-wheel, and eachdrives the same forward half a tooth, so that the combined action ofboth stepping-levers is necessary to cause the forward movement of theswitchwheel through the space of a complete tooth. The connectionexisting between the' steppinglevers and the actuating mechanismtherefor is as follows: Beneath the switchwheel W on either side of thebase-plate S are supported the electromagnets X. These magnets arepreferably secured at one end to the metallic yoke S', which in its turnis rigidly fastened to the base-plate S. The holes in the metallic plateS' for the passage of the screws which attach the electromagnet Sthereto are preferably slot-shaped in order to permit adjustment of themagnets relative to the position of the armature t, which is used inconnection therewith. The armature t is arranged across one face of theelectromagnets X and is supported by means of the rods r and r', whichserve to connect the steppinglevers V and V'. The rod r extends from thestepping -lever V' through a suitable opening formed in the base-plate Sthrough the armature t. The portion of the rod which extends through thearmature t is screw-threaded, and the locking-nuts r2 and r3, which aremounted thereon on both sides of the armature, permit adjustment of therelative position of the stepping-levers and the secure fastening ofsaid rod r to the armature. Connection between the armature and thestepping-lever V is elfected by means of the forked lever 1"'. Thelength of the connection between the two stepping-levers V and V' issuch that one of the stepping-levers is always in engagement with theswitch-wheel and the other stepping-lever out of engagement therewith.Normally when the circuit through the receiver is open and the armaturet is not in contact with the poles of the electromagnet X thestepping-lever V is held in engagement with the toothed periphery of theswitch-wheel by the action of the spring q. The spring q is, however,adapted to yield and permit outward movement of the stepping-lever V'each time the armature t is energized. It is to be noted that acam-shaped slot is formed in the yoke S' to permit the passage of therod r,which in part establishes the connection between thestepping-levers V and V'.

The operation of my receiver is as follows: The base-plate S and allparts in connection therewith are connected with the ground through theleading-wire Z' and the. battery Z2, which furnishes the current for theoperation of the entire system. Whenever the circuit through thetransmitter is completed by the action of the circuit making andbreaking device and the'electromagnets X are accordingly energized, thearmature tis attracted and the stepping-levers V and V' act to carry theswitch-wheel S forward through a distance equal to half a tooth. Whenthe circuit through the transmitter is broken, the stepping-levers V andV' serve to carry the switch-wheel through a distance equal to anotherhalf a tooth, and thus to cause the contact-sprin g T to make connectionwith the contact-point next adjacent to that with which it waspreviously in contact. The step-bystep movement of the switch-wheel ofthe receiver takes place with each making and breaking of the circuitthrough the transmitter and results in causing the switch-wheel of thereceiver to always coincide in position with the dial of the transmitterand to always establish the connection between the service instrument ofthe subscriber to whom the receiver and transmitter belong and theservice instrument of the subscriber whose name, number,or otherdesignation appears beneath the panel g on the face of the transmitter.

Operation of the system.-The operation of the transmitter and receiverin the system in which I especially design to use them, although theymay also be used in connection with other systems, if desired, can beeasily understood from the diagrammatic view of an automatictelephone-exchange system of three subscribers, which is shown in Fig.10.

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It will be there seen that a switching-wire Z connects the base-plate ofeach transmitter and all parts in connection therewith with thebase-plate of each receiver and all parts in connection therewith, thatthe circuit making and breaking spring of each transmitter is connectedto the ground by a leading-wire Y, and that the electromagnet of eachreceiver is also grounded through a corresponding leading-wire Z'. Thewires leading from the receivers to the ground are all connectedtogether, and an energizing-battery Z2 is introduced between thereceivers and the ground. Each of the contact-points of the receivers ofthe systems is connected to the service instrument, such as a telephone,of lthe subscriber whose number corresponds with the number of suchcontactpoint by service-wire M, and also to the contact-points of theremaining receivers of the system which bear the same number. Normallylthe contact-spring secured to the switch-Wheel of each receiver makescontact with the contact-point corresponding to the subscriber to whomsuch receiver belongs, and the name of the subscriber appears beneaththe panel g on the face of his transmitter. When it is desired toestablish any desired connection, the dial of the transmitter isrevolved until the name of the subscriber with Whom the connection isdesired to be established appears beneath the panel gon the face of thesame. While this movement has been taking place, the switch-wheel of thereceiver has been correspondingly revolved through the operation of thesteppinglevers provided therefor, and the contactspring which is fixedto the switch-wheel has moved a distance corresponding to the movementof such switch-wheel of the receiver or of the dial of the transmitterand has stopped when in contact with a contact-point corresponding withthe name, number, or other designation of the subscriber whose nameappears beneath the panel g on the face of the transmitter. Connectionis thus established between the subscriber who has been operating histransmitter and the subscriber whose name appears beneath the panel ofthe face of such transmitter. If desired, more than two subscriberscanplace themselves in communication at the same time by successivelyestablishing connection with each other through the use of theirtransmitters.

It is apparant that my invention is not restricted to the details of theconstruction which I have described herein, and I do not limit myself tothe precise details of such construction; but

What I claim as new, and desire to secure by Letters Patent, is'- 1. Ina transmitter, the combination with a shaft, a dial mounted thereon, anda wormwheel also mounted thereon, of a worm-shaft for rotating saidworm-wheel, a fork mounted thereon, anda contact-spring adapted to beengaged by said fork, substantially as described.

2. In a transmitter, the combination with a shaft, a dial mountedthereon, and a wormwheel also mounted thereon, of a worm-shaft a dial,and a shaft provided with means for rotating the same,and provided withflattened portions, of a spring bearing against the shaft and adapted toencounter the flattened portions thereof as the shaft revolves, therebycausing the shaft and dial to occupy fixed and definite positions whenat rest, and

a circuit making and breaking device arranged to operate as the dialrotates, the positions of rest of said shaft fixed by the springcorresponding to open-circuit positions of the circuit making andbreaking devices, substantially as described.

4. In a receiver, the combination with a circular series ofcontact-points, a switchwheel centrally located therein, said wheelhaving teeth circularly arranged thereon equal in number to the numberof contactpoints, and an arm carried by said switchwheel adapted tosuccessively make contact with said contact-points, of an electromagnet,an armature therefor, and two steppinglevers engaging said switch-wheeland connected to said armature, and adapted to move the wheel forwardwith a step-by-step movement, one on the forwardmovement of the armatureand the other on the backward movement thereof, substantially asdescribed.

5. In a receiver, the combination with a circular series ofcontact-points, a switchwheel centrally located therein, said wheelhaving teeth circularly arranged thereon equal in number to the numberof contactpoints, and an arm attached to said switchwheel and adapted tosuccessively make con- Atact with said contact-points, of steppingleversadaptedl to rotate said switch-wheel with a step-by-step movement, anelectromagnet, an armature therefor, and rods connecting said armaturewith said steppinglevers, substantially as described.

6. In a receiver, the combination with a circular series ofcontact-points, a switchwheel centrally located therein, said wheelhaving teeth circularly arranged thereon equal in number to the numberof contactpoints, and an arm attached to said switchwheel adapted tosuccessively make contact with said contact-points, of stepping-leversadapted to rotate said switch-wheel with a step-by-step movement, anelectromagnet, an armature therefor, and the adjustable rod r and forkedrod r connecting said armature with said stepping-levers, substantiallyas described.

7. In a receiver, the combination with a IoO IIO

r' connecting said armature and said stepping-levers, substantially asdescribed.

In testimony whereof I affix my signature in presence of two Witnesses.

EMERY A. CLARK. Vitnesses:

ELIZABETH HANKS, A. VAN WAGENEN.

